Multiple-function filler materials

ABSTRACT

A composition of matter includes a particle, a resin bonding functionality bonded to a first portion of the particle, and a lubricating functionality bonded to a second portion of the particle.

I. FIELD OF THE DISCLOSURE

The present disclosure relates generally to multiple-function fillermaterials.

II. BACKGROUND

In molding and making polymers, lubricants and additives are importantto the final product being produced. It is common for polymers tocontain additives, such as adhesives, surfactants, and filler materials.Lubricants are used to decrease frictional forces between materials,such as polymer:polymer friction, polymer:filler friction, filler:fillerfriction, and filler:metal friction. In injection molding, thelubricants are typically applied to the mold itself as a mold release toprevent the polymer from sticking to the metal surface.

III. SUMMARY OF THE DISCLOSURE

According to an embodiment, a composition of matter includes a particle,a resin bonding functionality bonded to a first portion of the particle,and a lubricating functionality bonded to a second portion of theparticle.

According to another embodiment, a process of forming amultiple-function filler material for a polymeric application isdisclosed. The process includes bonding a first set of functional groupsto a first portion of a particle. The process also includes bonding asecond set of functional groups to a second portion of the particle.

According to another embodiment, an injection molding process isdisclosed. The injection molding process includes blending amultiple-function filler material into a polymeric resin to form apolymeric blend. The multiple-function filler material includes aparticle, resin bonding functional groups on a first portion of theparticle, and lubricating functional groups on a second portion of theparticle. The injection molding process also includes performing aninjection molding operation that includes injecting the polymeric blendinto an injection mold to form a polymeric material.

Features and other benefits that characterize embodiments are set forthin the claims annexed hereto and forming a further part hereof. However,for a better understanding of the embodiments, and of the advantages andobjectives attained through their use, reference should be made to theDrawings and to the accompanying descriptive matter.

IV. BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a diagram showing a multiple-function filler material thatincludes a particle, resin bonding functional groups bonded to a firstportion of the particle, and lubricating functional groups bonded to asecond portion of the particle, according to one embodiment;

FIG. 2 is a diagram showing the addition of a first set of functionalgroups to a first portion of a particle, according to one embodiment;

FIG. 3 is a diagram showing the removal of an encapsulant material toexpose a second portion of the particle, according to one embodiment;

FIG. 4 is a diagram showing the addition of a second set of functionalgroups to the second portion of the particle, according to oneembodiment; and

FIG. 5 is a flow diagram showing a particular embodiment of a process offorming an injection molded polymeric material using themultiple-function filler materials described herein.

V. DETAILED DESCRIPTION

The present disclosure relates to multiple-function filler materials forpolymeric applications and processes for forming the multiple-functionfiller materials. The multiple-function filler materials of the presentdisclosure may act not only as a filler material (for rheology control,mechanical improvement, etc.) but also as an internal lubricant. In thepresent disclosure, a particle having two functionalities is compoundedas a filler material within the polymer to be molded. The functionalizedparticle has a functionality on one side that will bond with the polymerand act as a rheology control agent, mechanical property improver, etc.The other side of the functionalized particle has a functionality thatacts as a lubricating feature to prevent the polymer from sticking tometal surfaces during molding. The particles serve multiple purposeswhen added to the polymer, decreasing the number of additional stepsthat are required to prepare a mold for making polymeric parts orpotentially eliminating the need for an external mold release agent.Additionally, bonding the particles to the polymer matrix may improvethe mechanical properties of the polymer.

FIG. 1 is a diagram 100 showing a composition of matter (referred toherein as a “multiple-function filler material”) that includes a firstset of functional groups bonded to a first portion of a particle (e.g.,a silica particle) and a second set of functional groups bonded to asecond portion of the particle. In the particular embodiment depicted inFIG. 1, an unsaturated functionality is attached to one side of theparticle for bonding to a polymeric matrix. On the other side of theparticle is a lubricating moiety that acts as a mold release to preventthe particles from sticking to a metal injection mold during formation.As described further herein, the multiple-function filler material ofFIG. 1 may enable the elimination of processing steps associated withpreparing the molds and may promote adhesion to the polymeric matrix,which may improve the materials properties of the final part.

In the particular embodiment illustrated in FIG. 1, the first set offunctional groups (identified as “Functional Groups(1)” in FIG. 1)includes resin bonding functional groups, and the second set offunctional groups (identified as “Functional Groups(2)” in FIG. 1)includes lubricating functional groups. As described further herein withrespect to FIGS. 2-4, the multiple-function filler material of FIG. 1may be formed by attaching the resin bonding functional groups to anexposed surface of a silica particle and subsequently attaching thelubricating functional groups to another surface of the silica particle.In alternative embodiments, the lubricating functional groups may beapplied prior to the application of the resin bonding functional groups.

In a particular embodiment, the particle has a characteristic dimension(e.g., an average diameter) in a range of about 100 nanometers to about1 micrometer. As described further herein with respect to FIG. 2, theparticle may include a silica particle that is prepared through amodified Stober et al. synthesis (among other alternative processes). Asillustrated and described further herein with respect to FIG. 2, a firstportion of the particle is exposed in order to allow the resin bondingfunctional groups to be bonded to the first portion of the particle,while a second portion of the particle may be encapsulated within a wax(or other material). As illustrated and described further herein withrespect to FIG. 3, after bonding the resin bonding functional groups tothe first portion of the particle, the wax (or other material) may beremoved in order to expose the second portion of the particle. Asillustrated and described further herein with respect to FIG. 4,exposure of the second portion of the particle allows the lubricatingfunctional groups to be bonded to the second portion of particle.

Thus, FIG. 1 illustrates an example of a multiple-function fillermaterial that includes resin bonding functional groups bonded to a firstportion of a particle and lubricating functional groups bonded to asecond portion of the particle. As described further herein, themultiple-function filler material of FIG. 1 may be used in polymericapplications, such as injection molding of polymeric resins. The resinbonding functional groups may be selected to enable bonding of themultiple-function filler material to a polymeric resin (e.g., vinylfunctional groups for polymeric resins that include similar unsaturatedmoieties). In some cases, the lubricating functional groups may enableinjection molding operations to be performed without additionalprocessing steps associated with adding a lubricating release layer toan injection mold (e.g., a metal mold) prior to performing an injectionmolding operation. Additionally, the multiple-function filler materialof FIG. 1 may provide rheological control and/or improve mechanicalproperties of an injected molded polymeric material.

FIG. 2 is a diagram 200 showing the addition of a first set offunctional groups (e.g., resin bonding functional groups) to a firstportion of a (silica) particle, according to one embodiment. In order toproduce “Janus” particles (as described further herein), the particlesare first modified to protect a portion (referred to as the “secondportion” herein) of a surface of the particle. In a particularembodiment, such “Janus” particles may be produced using a wax emulsiontechnique (e.g., using a paraffin wax). In FIG. 2, the first portion ofthe particle is exposed while a second portion of the particle isencapsulated (e.g., in paraffin wax). As illustrated and furtherdescribed herein with respect to FIG. 3, after the first set offunctional groups have been attached to the first portion of theparticle, the wax encapsulant may be removed to expose the secondportion of the particle. As illustrated and further described hereinwith respect to FIG. 4, the second set of functional groups (e.g.,lubricating functional groups) may attached to the second portion of theparticle to form a multiple-function filler material (e.g., themultiple-function filler material of FIG. 1).

In the example of FIG. 2, the first set of functional groups to beattached to the particle include resin bonding functional groups (e.g.,vinyl groups). As illustrated and further described herein with respectto the examples of FIGS. 3-4, the second set of functional groups to beattached to the particle include lubricating functional groups. In othercases, the first set of functional groups to be attached to the particlemay include the lubricating functional groups, and the second set offunctional groups to be attached to the particle may include the resinbonding functional groups. Additionally, while FIG. 2 illustrates anexample of the addition of vinyl functional groups to a silica particle,one of ordinary skill in the art will appreciate that alternativefunctional groups and/or particles may be utilized. Illustrative,non-limiting examples of alternative resin bonding moieties may includeamines, epoxies, allyls, or acrylates that may be selected for aparticular polymeric resin type that the multiple-function fillermaterial is to be bonded to prior to an injection molding operation.

In a particular embodiment, silica particles may be produced through amodified Stober synthesis. Utilizing a silica precursor (e.g.,tetraethoxysilane (TEOS)), ammonia, water, and a solvent may enableproduction of particles that have diameters in the nanometer size rangeup to the micron size range. By varying the water concentration in thesynthesis, the particle's diameter can be varied. After synthesis,particles may be removed from their mother liquor solution to halt thegrowth of the particles and to obtain the desired particle size. Throughthe process of centrifugation and solvent washes, particles may beremoved from residual catalyst and precursor monomer. Particles may thenbe removed from solution in vacuo for further processing.

Prophetic Example: Synthesis of Silica Particles

Particles may be prepared through a modified Stober et al. synthesisusing anhydrous ethanol (200 proof), ammonia (2M), deionized water, andtetraethoxysilane (TEOS). TEOS may be distilled prior to use. Ethanol(5.38 mL) and TEOS (0.38 mL) may be added to a 20 mL scintillation vialand shaken to mix. In a separate vial, 2M ammonia (3.75 mL) anddeionized water (0.49 mL) may be added and shaken to mix. The ammoniasolution may then be poured into the ethanol/TEOS solution and left tostir for about 24 hours. After a suitable reaction period, particles maybe centrifuged and rinsed with ethanol multiple times (e.g., at least 3times) to remove residual monomer, yielding silica nanoparticles. Thefinal molar ratio of TEOS:ammonia:water may be 1.00:4.39:15.95. Thesilica nanoparticles may have a characteristic dimension (e.g., anaverage diameter) of about 200 nanometers.

To form “Janus” particles, the silica particles may be modified toprotect a portion (referred to as the “second portion” herein) of asurface of the particle. In preparation of such particles, an emulsionmay be fabricated. Silica particles may then be dispersed in anethanol/water solution at an elevated temperature (to melt the wax thatwill be added later) and then mixed. The particle mixture may be mixedwith cetyl trimethylammonium bromide (CTAB) to partially hydrophobizethe surface of the particle. A low concentration of CTAB may be used inorder to avoid the creation of a bilayer at the surface of the particle.The CTAB may cause the particle to favor the adsorption at the oil-waterinterface. Paraffin wax may then be added to the particle suspension,and the mixture may be vigorously stirred at elevated temperature. Aftercooling (e.g., to room temperature), the paraffin wax may solidify intosolid droplets with the nanoparticles partially extending from thesurface of the droplets (as shown on the left side of FIG. 2). Thedroplets (with particles extending from the surface) may then be washedwith an acid to remove CTAB and to expose a “bare” silica particlesurface.

As shown on the right side of FIG. 2, the first portion of the silicaparticle may be functionalized to include the resin bonding functionalgroups (e.g., vinyl functional groups). In a particular embodiment, thecolloidosomes (e.g., the wax droplets having the silica particlespartially embedded) may be reacted with a vinyl chloride solution toyield particles having resin bonding chemistries (vinyl functionalgroups). Illustrative, non-limiting examples of alternativefunctionalities for bonding to resins may include amines, epoxies,allyls, or acrylates.

Prophetic Example: Silica Particle Functionalization with Resin BondingFunctional Groups

Silica particles with vinyl groups (“resin bonding functional groups”)may be prepared using a modified Perro et al. paraffin-in-wateremulsion. Silica particles may be dispersed in an ethanol/water (6.7%,w/w) solution and heated to 65° C. To the suspension, cetyltrimethylammonium bromide (CTAB; C_(CTAB)/S_(silica)=5×10⁻⁶ molL⁻¹m⁻²−S_(Silica)) may be added. Paraffin wax (1.0 g, CAS no. 8002-74-2)may be added to the suspension. Once the wax has melted, the mixture maybe vigorously stirred (9000 rpm) for 80 seconds to form an emulsion. Theemulsion may be allowed to cool to room temperature to form soliddroplets of paraffin wax with embedded silica particles. The paraffinwax droplets may be filtered and dispersed into toluene (20 mL) andstirred. Vinyl chloride (0.1 to 10 weight percent) may be added, and themixture may be heated to about 35° C. The mixture may be allowed toreact for about 48 h followed by filtration and washing of the paraffinwax droplets with ethanol. Finally, the paraffin wax droplets may bedissolved in dichloromethane (DCM) to yield vinyl-modified silicaparticles.

Thus, FIG. 2 illustrates an example of the addition of a first set offunctional groups to a first portion of a particle. In the example ofFIG. 2, the first set of functional groups include resin bondingfunctional groups (e.g., vinyl groups) to enable bonding to a polymericresin prior to an injection molding operation. As illustrated andfurther described herein with respect to FIGS. 3-4, after the first setof functional groups have been attached to the particle, a secondportion of the particle may be exposed to attach lubricating functionalgroups that may enable the injection molding operation to be performedwithout the addition of a separate lubricating release layer.

Referring to FIG. 3, a diagram 300 illustrates the removal of thevinyl-functionalized particle of FIG. 2 from the encapsulating wax toexpose the second surface of the particle. As illustrated and furtherdescribed herein with respect to FIG. 4, the second set of functionalgroups (e.g., lubricating functional groups) may be attached to theexposed second portion of the particle to form a multiple-functionfiller material (e.g., the multiple-function filler material of FIG. 1).

FIG. 3 illustrates that, after addition of the first set of functionalgroups as shown in FIG. 2, the partially functionalized particles(vinyl-functionalized particles in the example of FIG. 2) may be removedfrom the wax encapsulant to yield the “Janus” type particles. Ahydrocarbon solvent, such as benzene, may be used to dissolve the wax.The particles may be centrifuged and decanted numerous times to yieldthe partially functionalized particles free of wax (as shown on theright side of FIG. 3).

FIG. 4 is a diagram 400 showing the addition of a second set offunctional groups (e.g., lubricating functional groups) to a secondportion of the (silica) particle, according to one embodiment. FIG. 4illustrates that the addition of the second set of functional groups tothe second portion of the particle results in a material that mayprovide multiple functionalities when used as a filler material inpolymeric applications. The resin bonding functional groups attached tothe first portion of the particle (e.g., vinyl groups) enable bonding toa polymeric resin prior to an injection molding operation, and thelubricating functional groups may enable the injection molding operationto be performed without the addition of a separate lubricating releaselayer.

FIG. 4 illustrates that functionalization may include reacting a silanematerial including multiple fluorine groups with the exposed portion ofthe particle to render the exposed surface lubricious. In the particularembodiment illustrated in FIG. 4, the silane material includestrichloro(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl)silane.In other embodiments, alternative and/or additional materials may beselected to provide sufficient lubricating characteristics for aparticular injection molding operation.

The resulting multiple-function filler material may be blended intopolymeric matrices having the same unsaturated functionality as that ofthe particles. The particles, when blended, are allowed to react withthe polymer and form a bond to “lock” the particle in place with thepolymer. If additional rheology control is required, additionalmaterials may be added. The resulting particle having an abundant amountof fluorine groups may remove the need for additional lubricants duringthe molding process. The lubricity of the polymer can be tailored bychanging the “Janus” particle filler content and/or varying the numberof lubricating functional groups (e.g., fluorine groups in the examplesilane material of FIG. 4). In a particular embodiment, a weightpercentage of the multiple-function filler material that is added to thepolymeric resin may be in a range of 10 to 40 weight percent, such as ina range of 10 to 30 weight percent, or in a range of 10 to 20 weightpercent.

Prophetic Example: Silica Particle Surface Modification with LubricatingFunctional Groups

To a round-bottom flask, toluene (20 mL) may be added and stirred (e.g.,with a magnetic stir bar), and 1 g of vinyl-modified “Janus” silicaparticles may be added, followed by the dropwise addition oftrichloro(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl)silane(0-10 wt %) to the mixture. The mixture may then be allowed to react forabout 24 h at about 35° C. After reaction, the mixture may be cooled toroom temperature and then filtered and washed with ethanol several timesto remove excess silane. The final product may then be dried in vacuo.

FIG. 5 is a flow diagram that illustrates a particular embodiment of aprocess 500 of forming a multiple-function filler material. In theparticular embodiment illustrated in FIG. 5, the process 500 includesblending the multiple-function filler material into a polymeric resinprior to an injection molding operation. Resin bonding functional groupsprovide the function of bonding the particle to a polymeric matrix, andlubricating functional groups provide the function of enabling releaseof a polymeric material from an injection mold. In a particularembodiment, the multiple-function filler material may be formedaccording to the process described herein with respect to FIGS. 2-4.

In the particular embodiment illustrated in FIG. 5, operationsassociated with an example process of producing a multiple-functionfiller material are identified as operations 502-504, operationsassociated with blending the multiple-function filler material into apolymeric resin are identified as operation 506, and operationsassociated with forming an injected molded polymeric material areidentified as operations 508-510. It will be appreciated that theoperations shown in FIG. 5 are for illustrative purposes only and thatthe operations may be performed in alternative orders, at alternativetimes, by a single entity or by multiple entities, or a combinationthereof.

The process 500 includes bonding a first set of functional groups to afirst surface of a particle (e.g., a silica particle), at 502. In somecases, the first set of functional groups to be applied to the particleinclude resin bonding functional groups, and a second set of functionalgroups to be applied to the particle include lubricating functionalgroups. For example, as illustrated and further described herein withrespect to FIG. 2, resin bonding functional groups (e.g., vinyl groups)may be applied to an exposed surface of the particle to form avinyl-functionalized particle. As illustrated and further describedherein with respect to FIG. 3, after functionalization of the firstsurface of the particle with the first set of functional groups, theparticle may be removed from the wax encapsulant to expose a secondsurface of the particle for subsequent functionalization.

The process 500 includes bonding a second set of functional groups to asecond surface of the particle to form a multiple-function fillermaterial, at 504. When the first set of functional groups bonded to theparticle (at 502) include resin bonding functional groups, the secondset of functional groups include lubricating functional groups. Forexample, referring to FIG. 4, the lubricating functional groups may bebonded to a second surface of the vinyl-functionalized particle to formthe multiple-functional filler material. In alternative embodiments,while not shown in the examples depicted in FIGS. 2-4, the first set offunctional groups applied to the particle (at 502) may includelubricating functional groups, and the second set of functional groupsapplied to the particle (at 504) may include resin bonding functionalgroups.

In the particular embodiment illustrated in FIG. 5, the process 500 alsoincludes blending the multiple-function filler material into a polymericresin, at 506. For example, the multiple-function filler material formedaccording to the process described herein with respect to FIGS. 2-4includes vinyl functional groups for binding the silica particle to apolymeric resin that includes similar unsaturated functional groups. Inalternative embodiments where the resin bonding functional groupscorrespond to alternative moieties (e.g., amines, epoxies, allyls,acrylates, etc.), the silica particle may be bound to a polymeric resinthat includes similar moieties.

In the particular embodiment illustrated in FIG. 5, the process 500further includes injecting the polymeric resin into an injection mold,at 508, and releasing the polymeric material from the injection mold, at510. In some cases, the injection mold may include a metal mold that hasnot been surface-modified to include a separate lubricant release layer.The lubricating functional groups of the multiple-function fillermaterial of the present disclosure may enable a polymeric material to beremoved from the injection mold (e.g., a metal mold) without theadditional processing step of applying a lubricant (e.g., apolytetrafluoroethylene (PTFE) spray) to the metal mold prior toinjection molding.

Thus, FIG. 5 illustrates an example of a process of forming amultiple-function filler material, blending the multiple-function fillermaterial into a polymeric resin, and forming an injected molded plasticmaterial by injecting the polymeric resin into an injection mold. Theresin bonding functional groups enable bonding of a particle (e.g., asilica filler particle for rheological control, etc.) to the polymerprior to injection molding, and the lubricating functional groups enablea formed material to be removed from an injection mold without the needto add a separate lubricating release layer to the injection mold priorto the injection molding operation.

The previous description of the disclosed embodiments is provided toenable any person skilled in the art to make or use the disclosedembodiments. Various modifications to these embodiments will be readilyapparent to those skilled in the art, and the generic principles definedherein may be applied to other embodiments without departing from thescope of the disclosure. Thus, the present disclosure is not intended tobe limited to the embodiments shown herein but is to be accorded thewidest scope possible consistent with the principles and features asdefined by the following claims.

The invention claimed is:
 1. A process of forming a multiple-functionfiller material for a polymeric application, the process comprising:bonding a first set of functional groups to a first portion of aparticle; bonding a second set of functional groups to a second portionof the particle to form a multiple-function filler material; andremoving the particle from an encapsulant after bonding the first set offunctional groups to the first portion of the particle to expose thesecond portion of the particle for bonding the second set of functionalgroups to the second portion of the particle.
 2. The process of claim 1,wherein the first set of functional groups includes resin bondingfunctional groups, and wherein the second set of functional groupsincludes lubricating functional groups.
 3. The process of claim 2,wherein the particle includes a silica particle.
 4. The process of claim3, wherein the resin bonding functional groups are bonded to the silicaparticle using a vinyl chloride solution.
 5. The process of claim 3,wherein the lubricating functional groups are bonded to the silicaparticle using a silane material that includes multiple fluorine groups.6. The process of claim 5, wherein the silane material includestrichloro(3,3,4,4,5,5,6,6,7,7,8,8,9,9,10,10,10-heptadecafluorodecyl)silane.7. The process of claim 1, wherein the first set of functional groupsincludes lubricating functional groups, and wherein the second set offunctional groups includes resin bonding functional groups.